Rifle nut



D. WILLIAMS April 2, 1963 RIFLE NUT Filed Aug. 8, 40 7 3,8358% Patented Apr. 2, 1963 3,683,586 RULE NUT Deloss Williams, New York, N.Y., assignor to Qirreago Pneumatic Toni Company, New York, N.Y., a corporation of New .iersey Filed Aug. 0, 1961, Ser. No. 1369,4983 9 Qlaims. (Cl. 74-4243) This invention is directed to improvements in rifle nuts and in their arrangement in rifle bar reverse rotation rock drills of the type which are adapted for driving threaded sectional drill rod and threaded couplings.

Rock drills of this type are well known and are used in drilling holes of various depths. In general, they include a striking bar which is threadedly associated with a threadedly coupled train of sectional drill red at the end of which is threaded a drill bit. During the operation of the drill the striking bar is subjected to repeated pounding by a reciprocating pneumatically powered hammer piston. The operations of the drill are controlled by a conventional rifle bar reverse rotation mechanism associated with a rifle nut mounted in the head of the piston.

The rotation mechanism enables the operator to selectively set the drill for normal drilling operation in which the reciprocating piston is accompanied by intermittent turning thereof and of the striking bar to a limited degree in a particular direction; or to set the drill for reverse operation in which the reciprocating piston is accom panied by intermittent turning of the piston and of the striking bar in the opposite direction; or to set the drill for neutral operation in Which the reciprocating piston is not accompanied by any compelling rotation thereof or of the striking oar. These diiferent operations are used at different times as required in Working the drill. In general, the normal operation of the drill serves to efiect drilling of the hole and rotation of the bit to change the biting relation of the latter to the ground. It also serves in tightening the couplings of the drill rod train. Neutral operation of the drill may be used in effecting a repeated pounding action on the drill rod train so as to loosen the couplings preparatory to separating the train from the striking bar in order to add or retrieve a length of drill rod from the train; or may be used as a means of retrieving or loosening a stuck drill rod train from its hole. Reverse operation of the drill may be used in unscrewing the striking bar from the drill rod train and in uncoupling the sections of the latter.

All of the foregoing operations of the drill exert various strong thrust and torque forces upon the rifle nut. A rifle nut having a threaded periphery is known; but if it is used in a rock drill having a rifle bar reverse rotation mechanism, the various forces acting on the nut will tend to unscrew and back it out of its socket, the result of which may prove seriously damaging to various internal parts of the drill.

A rock drill using sectional drill rod and having rifle bar reverse rotation mechanism is disclosed in US. Patent 2,910,046, issued October 27, 1959 to E. B. Lear. In this patent the rifle bar is associated with a hammer piston by means of a threaded rifle nut, but a snap ring is arranged in the hammer piston to block the rifle not from unscrewing or backing out of its socket during the different operations of the drill.

A general object of this invention is to provide a rifle nut for use in rock drills using sectional drill rod and having rifle bar reverse rotation mechanism, which rifle nut does not have the deficiencies of a threaded rifle nut and which does not need a retaining ring to retain it in its socket regardless of the direction of the forces applied to it during the various operations of the drill.

It is another object of this invention to provide in a rock drill an improved and practical rifle nut and hammer piston association, in which the rifle nut does not have a threaded engagement with the hammer piston, and yet will not loosen in or back out of its socket regardless of the selected operation to which the drill is subjected.

It is a further object of this invention to provide an unthreaded rifle nut and hammer piston association in which the rifle nut is caused to become impacted in its socket under reciprocating action of the piston, and wherein the rifle nut is so arranged in its socket that it does not turn therein despite the application of adverse strong torque forces to it in one direction or the other.

It is a still further object of this invention to provide an unthreaded rifle nut for a rock drill, which will become tighter in its socket as the drill operates.

The foregoing as well as other objects and advantages will appear more fully from the following description taken in connection with the accompanying drawings:

FIG. 1 is a fragmentary view of a rock drill embodying the invention;

FIG. 2 is an enlarged sectional view of the hammer piston with the rifle nut press fitted therein;

FIG. 3 is a top end view of the rifle nut including a fragmentary portion of the surface of the surrounding piston head;

FIG. 4 is a vertical section of the rifle nut itself taken on the line 4-4 of FIG. 3; and

FIG. 5 is a View similar to FIG. 2 but showing the rifle nut tightened in a fully impacted condition.

Reference is now directed to the several figures of the drawings for a more detailed understanding of the invention. The invention is illustrated as being incorporated in a rock drill 10 of the drifter type using sectional drill rod, such as the drill disclosed in US. Patent 2,910,046. The drill is mountable in conventional manner upon a guide shell, not shown, for relative axial movement along the latter. The rock drill includes a housing 11 providing a piston cylinder 12 in which the enlarged head portion 13 of the hammer piston 14 is pneumatically reciprocable. Depending from the piston head is an elongated reduced cylindrical shank 15, the bottom end 16 of which serves as a hammer to pound a striking bar 1'7. The latter is engaged in conventional manner for rotation with a chuck member 18 of the rock drill. The striking bar has a reversely threaded end, not shown, which is adapted to be threadedly coupled in the usual manner to the usual train of sectional threadedly coupled together drill rod.

The chuck 18 is engaged by means of longitudinal splines 19 thereon with spline grooves 21 extending longitudinally along the lower portion of the piston shank 15'. By means of this splined engagement the piston has axial slidable movement relative to the chuck against the striking bar 17; and by means of the splined connection 19 'and 21 any rotation that may be imparted to the piston in one direction or the other is transmitted by the chuck 18 to the striking bar '17 and to the associated drill rod train.

The piston has axial slidable movement along the usual rifle bar 22, and at predetermined times also has rotative movement relative to the latter. This mode of movement is enabled by a rifle nut 23 press fitted in a socket or recess 24 of the piston. The nature of the rifle not as well as the nature of the associated recess, and the manner in which the rifle nut is associated with the recess represent the improvement in rock drills which is provided by the I present invention.

The rifle nut 23 has the usual axial bore 25 and helical or inclined splines 26 formed in the wall of the latter for working reception of a rifle bar therein. The rifle bar 22 has the usual elongated shank 27 formed with elongated helical or inclined splines 28 slidably mated with the splines of the rifle nut. The piston has the usual elongated bore 29 which is coaxial with that of the rifle nut and is of such diameter that it is adapted to freely receive the shank 27 of the rifle bar as the piston reciprocates relative to the latter.

. Associated with the rifle bar is conventional manipulative rifle bar reverse rotation mechanism 31 (FIG. 1) such as that described in US. Patent 2,910,046. In general, this reverse rotation mechanism includes a manipulative key 32 having three selectable positions. When the key is turned by the operator to a first or normal position,- it acts through a pinion 32a and associated pawl shift mechanism 33 to shift an arrangement of pivoted pawls 3.4 in such manner relative to a ratchet head 35 of the rifle bar so as to restrain rotation of the rifle bar in a certain direction, and to permit free rotation of the rifle bar in the opposite direction. When the key is turned to a second or reverse position, not shown, its effect through the shift mechanism and pawls on the rifle bar is opposite to that obtained in the first position of the key. And, when the key is turned to' a neutral or intermediate position, not shown, it acts througi the pinion 32a and shift mechanism 33 to shift all of the pawls 34 clear of the ratchet head 35 of the rifle bar so that the latter is unrestrained against rotation.

. The splines 28 .of the rifle bar cooperate with those 26 of the rifle nut in conventional manner, so that when the key 32 is in its first position for normal operation of the drill the rifle bar 22 rotates freely as the piston 14 moves forwardly on its impact stroke, and the piston turns or rotates relative to the restrained rifle bar during the return stroke of the piston. This action is accompanied during the return stroke of the heavy piston by the transmission of considerable torque force to the rifle nut. The tool is set for normal operation when drilling a hole; and the rotation of the piston which is transmitted through the chuck means 18 to the striking bar 17 serves to tighten the couplings, not shown, in the sectional drill rod train as well as to change the biting position'of the usual drill bit at the end of the train relative to the earth.

The reverse .action takes place in the operation of the drill when the key .32 is in its reverse position. In this case the forward stroke of the piston is accompanied by the transmission of considerable torque force to the rifle nut in a direction reverse to that which takes place in the normal position of the key. Reverse operation of the drill may be used for unscrewing in conventional manner the striking bar 17 from the drill rod train and in uncoupling the latter.

When the key 32 is in its neutral position for neutral operation of the drill, the rifle bar is unrestrained and accordingly the piston is not compelled by its association with the rifle 'bar to rotate in either direction. Neutral operation of the drill is usually employed to apply repeated pounding action of the piston against the striking bar so vas to .iar a stuck drill rod train loose from its hole, or to loosen the couplings when building up the drill rod train or when retrieving it from a hole. The repeated pounding action of the piston is accompanied by the transmission of considerable thrust forces in various direc-' in such manner that the rifle nut not only remains fast in its socket but also becomes tighter therein.

The improved rifle nut 23 of the present invention (FIG. 4) has a fiat circular top face 36, and has parallel to the latter a flat relatively reduced circular bottom face 37. Adjacent the latter is a short coned annular surface or shoulder 38, the taper of which is relatively steep. The body proper 39 of the rifle nut extends from the upper end B of the coned shoulder surface 38 to the top edge A of the nut; and :has a .coned taper. The large diameter of thetaper'is' defined at the top edge A of the nut; and the surfaces 38 of the nut; and the upper annular wall surface proper 42 of the recess has a taper corresponding to that of the main body portion 39 of the nut. When the nut is received in the recess, the wall surfaces 38 and 39 of the nut are respectively parallel to the corresponding wall surfaces 41 and 42 of the recess.

The 'coned surface 41 of the recess 24 serves as a stop or seat which limits the extent to which the rifle n-ut may be forced down into the recess. It is to be noted (FIG. 2) that the vertical height of the recess, when measured from the top edge A thereof to the seat at C, is a little greater than the vertical height A to B of the nut. The nut is tightly press fitted in the recess 24; and has a normal condition therein wherein a space 43 exists between the coned surface 38 of the nut and the conical seat 41 I of the recess, as in FIGS. 1 and 2. In this normal condition the top surface of the nut is flush with that of the piston. In order to obtain a tight press fit of the nut in the recess, the large and small diameters A and B of the taper of the body proper of the nut are slightly greater than the corresponding diameters of the recess.

A lock pin 44, fitted in part in a longitudinal gr ove 45 of complementary radius formed in the wall of the recess, and fitted in part ina longitudinal groove 46 of complementary radius in the nut, further secures and restrains the nut against rotation relative to the piston head, re-

gardless of the direction of torsional thrusts imparted to the nut by rotary action of the piston. The groove 45 opens through the top surface of the piston head, and provides a shoulder 47 at its bottom end as a stop for the 3 lock pin. The groove 46 opens through the coned surpiston head.

When the rifle nut is, as in FIGS. 1 and 2, fitted in the recess 24 of the piston head, the bore .25 of the nut is coaxial with the lower bore 29 of the piston and has a diameter slightly less than that of the latter, whereby the splined shank 27 of the rifle bar may, in moving through the nut, be freely admitted into the bore 29 of the piston.

The necessity of the lock pin 44 and the associated grooves 45 and 46 may be dispensed with by roughing the tapered outer surface 39 of the nut. The tight press fit of the nut in its recess, together with the added frictional engagement offered by the roughened surface of the nut, would securely restrain the nut against axial movement as Well as against rotation, regardless of the direction of torsional thrusts imparted to it by the hammer piston. It is understood that the wall surface 24 of the recess may also be roughened. The rifle nut 23 is preferably made of bronze metal.

The difference in length between the rifle nut and the recess whereby the space 43 is normally provided between the nut and its seat is of decided'advantage. During pounding actions of the hammer piston there is a reactionary downward thrust imparted to the rifle nut due to the inertia or mass of the nut. This thrust tends to force the nut downwardly in the recess toward its seat. Any

slight downward movement of the nut from the initial nor- 7 anal position in FIG. 2 causes the nut to become tighter and more firmly impacted in the recess, so that it Wfll resist all vibratory, torsional and other adverse forces ofthe drill, rifle bar, and piston acting upon it, and will be firmly held against endwise escape from the recess as well as against rotative movement relative to the recess.

FIG. 5 shows the rifle nut tightly impacted in its recess and moved down upon its seat. The space 49 (FIG. 2) normally existing between the pin 44 and the lip 48 is sufficient to enable the nut to move downward relative to the pin to its seat 41, as appears in FIG. 5.

While an embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. It is my intent, therefore, to claim the invention not only as shown and described herein but also in all forms and modifications thereof as may reasonably be construed to fall Within the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. In a rock drill including a rifle bar, a hammer piston reciprocable relative to the rifle bar having an axial bore in its head for reception of the rifle bar as the piston reciprocates, and a recess formed in the piston immediately above and coaxial with said bore, the recess having an internal wall surface of coned taper, the large diameter of the taper being at the top end of the piston, and the recess having an annular seat defining the bottom end thereof; a rifle nut in the recess having an axial Working engagement with the rifle bar, the rifle nut having an outer body surface of coned taper corresponding to that of the internal wall of the recess, and having a shoulder at the bottom end thereof complementing the seat of the recess, and the nut having a predetermined press fit in the recess wherein the soulder of the nut is normally clear of the seat below; wherein the shoulder and seat respectively of the nut and recess have a coned surface relatively steeper than the said tapers of the nut and recess.

2. In a rock drill as in claim 1, wherein at least one of the surfaces of coned taper is roughened whereby the rifle nut is frictionally restrained in the recess against relative rotative movement.

3. In a rock drill as in claim 1, wherein the riflle nut has a longitudinally extending groove in its tapered surface, the groove opening through the shoulder of the nut at one end and having an overhanging lip at its upper end; a mating groove is formed in the corresponding wall of the recess having an abutment at its bottom end and opening through the piston at its upper end; and a pin disposed in part in each of the grooves and locked therein against escape by the said abutment at one end and the lip at the other, the pin serving to lock the rifle nut in the recess against relative rotative movement.

4. In a rock drill as in claim 3, wherein the pin is normally seated upon said abutment of the groove. and is spaced from the overhanging lip a distance at least equal to the clearance normally existing between the shoulder at the bottom of the nut and the seat of the recess.

5. A rifle nut of the character described having a thickened body provided with an axial bore designed for working movement therein of a rifle bar; characterized by truncated top and bottom end wall surfaces, and by an annular body surface intermediately of said ends having a coned taper, the large diameter of the taper being at the upper end of the nut.

6. A rifle nut of the character described having a thickened body provided with an axial bore designed for working movement therein of a rifle bar, and having top and bottom parallel end walls, the bottom end wall being relatively reduced as compared to the top end wall; characterized by a main body portion having an outer surface of coned taper, the upper end of the nut defining the large diameter of the taper, a relatively steep coned surface adjacent the bottom wall and the main body portion, and the small diameter of the taper of the nut being defined by the junction point of the steep coned surface with the outer surface of the main body portion.

7. A rifle nut as in claim 6, wherein a keyway is formed longitudinally of the tapered surface of the main body portion, the keyway opening through the steep coned surface at its bottom end, and a lip forming part of the upper end of the nut closing over said end of the keyway.

8. A rifle nut as in claim 6, wherein the outer surface of coned taper is roughened.

'9. A rifle nut as in claim 6, wherein the rifle nut is formed of bronze metal.

References Cited in the file of this patent UNITED STATES PATENTS 317,113 Githens May 5, 1885 1,106,537 Beaudin Aug. 11, 1914 1,871,728 Nell Aug. 16, 1932 2,251,269 Curtis Aug. 5, 1941 2,755,069 Mosby July 17, 1956 2,910,046 Lear Oct. 27, 1959 

1. IN A ROCK DRILL INCLUDING A RIFLE BAR, A HAMMER PISTON RECIPROCABLE RELATIVE TO THE RIFLE BAR HAVING AN AXIAL BORE IN ITS HEAD FOR RECEPTION OF THE RIFLE BAR AS THE PISTON RECIPROCATES, AND A RECESS FORMED IN THE PISTON IMMEDIATELY ABOVE AND COAXIAL WITH SAID BORE, THE RECESS HAVING AN INTERNAL WALL SURFACE OF CONED TAPER, THE LARGE DIAMETER OF THE TAPER BEING AT THE TOP END OF THE PISTON, AND THE RECESS HAVING AN ANNULAR SEAT DEFINING THE BOTTOM END THEREOF; A RIFLE NUT IN THE RECESS HAVING AN AXIAL WORKING ENGAGEMENT WITH THE RIFLE BAR, THE RIFLE NUT HAVING AN OUTER BODY SURFACE OF CONED TAPER CORRESPONDING TO THAT OF THE INTERNAL WALL OF THE RECESS, AND HAVING A SHOULDER AT THE BOTTOM END THEREOF COMPLEMENTING THE SEAT OF THE RECESS, AND THE NUT HAVING A PREDETERMINED PRESS FIT IN THE RECESS WHEREIN THE SHOULDER OF THE NUT IS NORMALLY CLEAR OF THE SEAT BELOW; WHEREIN THE SHOULDER AND SEAT RESPECTIVELY OF THE NUT AND RECESS HAVE A CONED SURFACE RELATIVELY STEEPER THAN THE SAID TAPERS OF THE NUT AND RECESS. 